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Jupeb

2022/2023 JUPEB–BIOLOGY–THEORY ANSWERS

Posted by on November 14, 2022 0

 

(1a)

(i) Genes:

It is a basic unit of heredity and a sequence of nucleotides in DNA that encodes the synthesis of a gene product, either RNA or protein.

 

(ii) Alleles:

Allele is variant of a given gene. In genetics, genes normally exhibitdeviations or diversity: all alleles for a particular trait together make up the set of genetic information that defines a gene.

 

(iii) Homozygous organisms:

Homozygous, as related to genetics, refers to having inherited the same versions (alleles) of a genomic marker from each biological parent.

 

(iv) Heterozygous organisms:

Heterozygous, as related to genetics, refers to having inherited different versions (alleles) of a genomic marker from each biological parent. Thus, an individual who is heterozygous for a genomic marker has two different versions of that marker.

 

(v) Dominant allele:

A dominant allele is a variation of a gene that will produce a certain phenotype, even in the presence of other alleles.

 

(vi) Recessive allele:

A recessive allele is a variety of genetic code that does not create a phenotype if a dominant allele is present.

 

(vii) Test cross:

A test cross is an experimental cross of an individual organism of dominant phenotype but unknown genotype and an organism with a homozygous recessive genotype (and phenotype).

 

(viii) Sex-linked genes:

Sex-linked, as related to genetics, refers to characteristics (or traits) that are influenced by genes carried on the sex chromosomes.

 

(ix) Rhesus:

The Rhesus factor, or Rh factor, is a certain type of protein found on the outside of blood cells.

 

(x) Albinism:

A group of genetic conditions marked by little or none of the pigment melanin in the skin, hair, and/or eyes.

 

(1c)

Genetic variation is the difference in DNA among individuals or the differences between populations.

(6a)

Fertilization is defined as the union of two gametes. During fertilization, sperm and egg fuse to form a diploid zygote to initiate prenatal development.

 

(6b)

SEEDS

– After the fertilization, the ovule converts into the seed.

– The outer layer of the seed is known as the testa.

– Seed basically are used for reproduction, and it is the product of sexual reproduction of the plant.

– Seeds do not undergo a ripening process.

– Seeds contain a low amount of moisture compared to seeds, and its shelf life is comparatively high.

 

FRUITS

– After the fertilization, the ovary converts into the fruit.

– The outer layer of the fruit is known as the exocarp.

– Fruit does not represent reproduction units.

– Fruits undergo a ripening process and the plant hormone ethylene reasons ripening of numerous types of fruit.

– Fruits contain a high amount of moisture compared to seeds, and its shelf life is comparatively low.

 

(6c)

The flower is designed to start the process of reproduction. The female parts creates an unfertilized egg (ovule). The egg stay in the ovary and wait to be fertilized. The male parts (to be specific, the anther) produces pollen, that has the sperm needed to fertilize the egg.

(7a)

– The nucleus has diffused appearance due to scattered chromatin, the vesicular nucleus contains a central body called endosome or nucleoli. Nucleoli of apicomplexans have DNA, whereas amoeboids lack DNA in their endosome

Ciliates have micronucleus and macronucleus

 

– The plasma membrane encloses the cytoplasm and other locomotory projections like flagella, pseudopodia and cilia.

 

– Some of the genera have a membranous envelope called pellicle, which gives a definite shape to the cell. In some of the protozoans, epibiotic bacteria attach to the pellicle by their fimbriae.

 

– The cytoplasm is differentiated into outer ectoplasm and inner endoplasm, ectoplasm is transparent and endoplasm contains cell organelles.

 

– Some of the protozoa have cytostome for ingesting food. Food vacuoles are present, where ingested food comes. Ciliates have a gullet, a body cavity which opens outside.

 

– The central vacuole is present for osmoregulation, that removes excess water

Membrane-bound cell organelles, like mitochondria, Golgi bodies, lysosomes and other specialised structures are present.

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